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The first experimental work to produce transparent MgAl2O4 nano-ceramics was reported in this paper. The sintering characteristics of transparent nano-ceramics were investigated at relatively low temperature (800 ~ 1100°C) under ultrahigh pressure (2 ~ 5 GPa) using hydrostatic equipment. The morphologies
and phases of ceramics were observed by means of SEM and XRD, respectively. The grain sizes of the ceramics are shown to be less than one hundred nanometers, far smaller than the sizes of common transparent ceramics. Furthermore, the higher the sintering temperature and pressure are, the
greater the extent of densification is. At the same temperature, the higher the pressure is, the smaller the average grain size is. Under the same pressure, the higher the temperature is, the larger the average grain size is. The optimal sintering condition for preparing transparent nano-ceramics was also determined.

Abstract: The present paper is focused on ceramic–metal composites obtained via different
technologies which leads to different microstructures in terms of size and distribution of metal phase. Composites analysed in paper were produced by the following methods:(a) infiltration of porous ceramics by metal, (b) consolidation under high pressure and (c) sintering of ceramic powder coated by metal. Their microstructures were investigated by scanning and transmission electron microscopy methods. The three methods of composite fabrication employed in the present study result in specific spatial distribution and dispersion of metal phase. Presureless infiltration of porous ceramics by liquid metal is driven by capillary force and make it possible to produce microstructure with percolation of metal phase in ceramic matrix. The volume fraction of metal phase in this case depends on the size
of pores. The size of pores influence also the kinetics and extent of infiltration. Ceramic preforms with small size of pore are not fully infiltrated. This method is useful for composite with size of metal phase in the range of micrometers. Hot pressing under high pressure produces microstructures of composites with metal phase grain size in the range from nano to micrometers. Moreover, it allows to achieve the nanometric size of ceramic grains. In the case of ceramic powders covered by metal, compression and hot pressing preserves nanometric size of metal. The grain growth of ceramic grains is suppressed.

Abstract: XRD, SEM, bulk density and dielectric properties measurements were used to investigate the
effect of TiO2 nanopowder substitution for conventional TiO2 micro-powder on the sintering and electric
properties of PZT ceramics. Results revealed that the sintering temperature of dense Pb(Zr0.53Ti0.47)O3
ceramics was lowered about 50°C ~ 100°C when 20% and 40% of conventional TiO2 micro-powder was
substituted by TiO2 nanopowder. The electric properties were kept or even enhanced in the PZT ceramics
adopted the TiO2 nanopowder.

Abstract: Translucent AlN ceramics were fabricated using spark plasma sintering (SPS) technique with
3wt% CaF2 as sintering additive. The samples achieved 52.4% maximum transmittance in medium IR
region after 10 min holding time by spark plasma sintering at 1800°C and 30 MPa pressure in N2. The
results from XRD, SEM, TEM and EDX showed that the sintered bodies were densely compacted and
highly pure with fine grain size and uniform microstructures. No secondary phases were observed at the
grain boundaries and triple grain junctions, which guaranteed good optical property of the sintered bodies.

Abstract: Heat treatment is an effective means of structural adjustment and performance improvement of AlN ceramics. AlN ceramics prepared at high pressure with Y2O3 as a sintering aids were heat treated in a nitrogen flow atmosphere. The effects of heat treatment on microstructure and thermal conductivity of AlN ceramics were studied. The results show that the grain size of the AlN ceramics heat-treated at 970 °C for 2 h is significantly increased, the actual crystal morphology is realistic and the second phases are almost present at the grain boundaries or triple pockets compared with the samples without heat treatment, which thermal conductivity has reached 156.7 W/(m·K) from 77.3 W/(m·K). However, the pore size of AlN ceramics is increased and there is the phenomenon of anti-densification while the heat treatment time is extended to 4 h. The thermal conductivity of AlN ceramics heat-treated at 970 °C for 4 h is reduced to 92.6 W/(m·K).

Abstract: In this paper, the effect of Nb2O5 on the microstructure and dielectric properties of BaTiO3-based ceramics has been investigated. In the study，Nb2O5 is added to the BaTiO3-based ferroelectric material by conventional solid state synthesis. The structure is identified by X-ray diffraction method and SEM is also employed to observe the surface morphologies of the sample. The specimens of the ferroelectric doped with 2wt% Nb2O5 sintered at 1260°C for 1h exhibit attractive properties, its dielectric temperature coefﬁcient is lower than 15% over a wide temperature range from －55 to +180°C.